A conventional drilling unit, also denominated drilling rig by those skilled in the art, for use above ground and according to prior art comprises a carrier and a feeder having a drilling machine. The carrier frequently includes a chassis, which defines an engine house, which in turn accommodates an engine and a plurality of great power consumers, for example a compressor. Furthermore, the engine house accommodates one or more coolers having fans associated therewith. The coolers may include an engine cooler, a charge-air cooler, a hydraulic-oil cooler and a compressor cooler.
The fan(s) either sucks air from the engine house and presses it or sucks the air out through the cooler, depending of how the fan is located in relation to the cooler, upstream or downstream. Alternatively, the fan sucks or presses air from the surroundings through the cooler and further through the engine house. This means that either the cooler has been fed with air that has been warmed up in the engine house, by heat exchange with the engine, the compressor, etc., or air that has been warmed up during the passage of the cooler has been brought into the engine house.
Furthermore, a drilling unit creates much dust in the environment thereof because of rock being crushed in the operation. This dust is deposited everywhere on the machine in spite of equipment in the form of vacuum cleaner is onboard in order to take care of it. The typical dust handling equipment collects the dust and puts it in piles. However, these may whirl up when affected by, for example, wind or because of a vehicle driving through them. Dust is sucked up by the fan or fans of the drilling unit and is pressed or drawn through the engine house, in particular if the air is sucked up near the ground.